Redline

At red line there's no more power to be found. It's when you shift into the next gear the G force kicks in. :woohoo:
Steve

On a stock motor they are running out of steam by the redline, so not much to be gained. Also the forces on a reciprocating part are proportional to the square of the rpm, so forces multiply quickly...hence forged con rods smashing through crankcases with the power of a hand grenade.

For a tuned motor which 'breathes' a lot better,there can be gains, just you need to think what the limiting factors are. Generally valve bounce, when the springs can't close them fast enough -hence the heavy duty springs needed for a wild performance cam grind. Modern sports bikes can rev much higher as they have 16 valve heads with smaller and lighter valvetrain components.

These motors have generous clearances between the valves and piston so they take a lot of abuse. I was quite suprised myself exactly how much.

Pic below shows a graph of valve lift 20 degrees before and after TDC during the overlap period. This is a GPz615 project with +1 / +2mm oversize valves and a (mild) higher lift cam,




Even with bigger valves and more lift there is plenty of space between the valves. I used a 1.5mm thick washer over one and lifted the other to check for interference.



A longer duration cam with more lift and overlap and the clearances would be a lot less, but in factory tune these (550) motors are pretty bulletproof.

daveo wrote:

pete greek1 wrote: & If you're into the redline area & your transmission doesn't engage in the gear you're shifting in, your motor will rev well beyond the redline limit, & KABOOM, something's gonna give,
Pete

The Dynatek 2000 has an adjustable rev limiter in 500 rpm increments starting at 8500, which is redline on my tach...and my engine has no problem going there. Should I set it to 9000-9500 for the extra breathing room?

My LTD 1000 also redlines at 8 1/2, with the 1075 kit ported head, heavy duty springs RS 34's, it still feels like it's pulling at 8 1/2, but I have my Dyna 2000 set at 9 grand, I figure why take a chance on pushing it to the limit. seen people destroy their motors, even spitting out shims right thru the head
Pete

...seen people destroy their motors, even spitting out shims right thru the head

Shim under bucket for high rpm applications, one of the few design faults of the kz900 motor imo.

The Z1 design was dasicaly a service engine. The power was more than adequate at the time. But we always want MORE. :evil:
Steve

First and second gear and the race is over. I love it when I slam it into second at 9000 RPM. I rode my bike for 20 years until it started popping out of second. Not bad.
Steve